Poly(arylene ether)s and their blends with styrenic resins are highly valued for their tailorable combination of stiffness, ductility, heat resistance, and electrical resistance. The oxidative polymerization reactions used to prepare poly(arylene ether)s often produce a broad range of molecular weights. The precipitation methods typically used to isolated the poly(arylene ether)s from the polymerization reaction solution usually have little effect on the molecular weight distribution. Similarly, so-called total isolation procedures, in which a poly(arylene ether) is isolated via removal of all volatile components from a reaction mixture, have little effect on the molecular weight distribution of the poly(arylene ether) product. While it is possible to exert some control over the molecular weight of a poly(arylene ether) by varying the polymerization reaction conditions, it would be useful—both for research and for commercial applications—to have a convenient and economical method of fractionating an existing poly(arylene ether), that is, separating it into different molecular weight fractions. And it would be particularly desirable to have a fractionation method that produces fractions having different molecular weights but similar ratios of weight average molecular weight to number average molecular weight.